Adaptive input estimation method and fuzzy robust controller combined for active cantilever beam structural system vibration control

This paper studies the active vibration control of a cantilever beam structural system by combining the adaptive input estimation method with the fuzzy robust controller. The unknown inputs can be estimated using the measurement dynamic displacement of a beam structural system. That is to say, the adaptive input estimation method can estimate the dynamic inputs of every step time on-line, while the active component applies the same magnitude inverse force into the feedback control. The simulation results show that the proposed synthesis control system has disturbance compensation capability. It can suppress the vibration in a disturbance structural system more effectively and promote controller performance

Determination of Moving Tank and Missile ImpactForces on a Bridge Structure

A method to determine the moving tank and missile impact forces on a bridge is developed. The presentmethod is an online adaptive recursive inverse algorithm, which is composed of the Kalman filter  and therecursive least square estimator (RLSE), to estimate the force inputs on the bridge structure. The state equationsof the bridge structure were constructed by using the model superposition and orthogonal technique. Byadopting this inverse method, the moving tank and missile impact force inputs acting on the bridge structuresystem can be estimated from the measured dynamic responses. Besides, this work presents an efficientweighting factor applied in the RLSE, which is capable of providing a reasonable estimation results. The resultsobtained from the simulations show that the method is effective in determining the moving tank and missileimpact forces, so that the acceptable results can be obtained.Defence Science Journal, 2008, 58(6), pp.752-761, DOI:http://dx.doi.org/10.14429/dsj.58.170

Transient Load Recovery Using Strain Measurements and Model Reduction

A transient load is defined as a loading condition where the magnitude of the load changes rapidly in a short period of time. Impact loads are a common example of transient loading. It is well known that impact loads can have disastrous effect on the structure compared loads applied over a longer period of time. An identification of impact loads is an important aspect in the design of structures. A direct identification of applied force on a structure through use of force transducers is not possible under all situations. In such cases, the structural response could be used to recover the imposed loading. Various structural responses such as displacement, stress or strain could be used to recover the imposed loads. However, this thesis focuses on a use of strain data to recover impact loads acting on a component. The strain data is extracted by placing strain gages at different locations on the component. A selection of the location for strain gages is tricky because the accuracy of the load recovery is sensitive to the position of the sensors. A D-optimal technique is used in this thesis to determine the optimum location of sensors so that most accurate results for load estimates are obtained. With sensors placed at the optimum locations, the strain data was extracted. The extracted strain data was used in conjunction with component’s modal data to approximate mode participation factors. The approximated mode participation factors and displacement mode shapes were next used to approximate displacements, velocities and accelerations. Finally, this information was used to estimate the loads acting on the component. A drawback of this approach is that it requires modal information of the entire structure be available. However, practical computational considerations limit the use of information of all modes. To overcome this difficulty, reduced order modeling based on Craig-Bampton model reduction is used. It is seen that Craig-Bampton reduction allows for an accurate estimation of imposed loads while utilizing only a small subset of available modal information